The　single　thermal　energy　storage　tank　(STEST)　has　been　extensively　investigated　because　of　the　advantage　of　cost　and　efficiency.　This　research　presents　heat　discharging　performance　of　STEST　using　coil　heat　exchanger　(CHE)　with　annular　baffle　at　different　working　conditions.　The　heat　discharging　performance,　flow　field　and　temperature　distribution　of　different　parameters　of　the　annular　baffle　are　presented　and　discussed.　The　results　show　that　the　heat　discharging　time　decreases　with　an　increase　inlet　air　velocity　of　the　CHE.　The　heat　discharging　efficiency　is　up　to　95.7%　in　this　study,　and　the　heat　discharging　time　can　reach　to　18.7　hours.　In　addition,　optimal　dimensionless　diameters　of　annular　baffle　are　D-b/D-t　=　0.6,　H-s/H-t　=　0.075　and　H-x/H-t　=　0.050　(H-s　is　the　height　from　the　top　of　baffle　to　the　top　of　tank.　H-t　is　the　height　of　the　tank.　H-x　is　the　height　from　bottom　of　the　baffle　to　the　bottom　of　the　tank).　The　efficiency　of　heat　discharging　process　can　be　enhanced　with　optimal　dimensions　of　the　annular　baffle.　This　study　presents　a　direct　practicable　guide　to　design　the　STEST.